US20050168698A1 - Video projector and method for shifting projected picture - Google Patents
Video projector and method for shifting projected picture Download PDFInfo
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- US20050168698A1 US20050168698A1 US11/043,266 US4326605A US2005168698A1 US 20050168698 A1 US20050168698 A1 US 20050168698A1 US 4326605 A US4326605 A US 4326605A US 2005168698 A1 US2005168698 A1 US 2005168698A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/2092—Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3141—Constructional details thereof
- H04N9/317—Convergence or focusing systems
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/08—Arrangements within a display terminal for setting, manually or automatically, display parameters of the display terminal
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2340/00—Aspects of display data processing
- G09G2340/04—Changes in size, position or resolution of an image
- G09G2340/0407—Resolution change, inclusive of the use of different resolutions for different screen areas
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2340/00—Aspects of display data processing
- G09G2340/04—Changes in size, position or resolution of an image
- G09G2340/0464—Positioning
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2360/00—Aspects of the architecture of display systems
- G09G2360/18—Use of a frame buffer in a display terminal, inclusive of the display panel
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- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Theoretical Computer Science (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Projection Apparatus (AREA)
- Controls And Circuits For Display Device (AREA)
- Liquid Crystal (AREA)
- Liquid Crystal Display Device Control (AREA)
- Transforming Electric Information Into Light Information (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
A video projector includes a scaler unit, a display device, a projection lens, and a control unit. The scaler unit writes an input video signal into a frame memory and scales the number of pixels of the input video signal to any number of pixels when the input video signal is read out from the frame memory. The display device displays a picture based on the video signal. The projection lens projects the picture displayed on the display device onto a screen. The control unit controls the scaler unit so as to scales the number of pixels of the input video signal to a smaller number of pixels than the maximum displayable number of pixels of the display device. The scaler unit shifts the picture displayed on the display device to a desired position in the displayable region on the display device by changing the timing of the vertical and horizontal superimposition of the video signal according to an instruction from an operating device.
Description
- This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-24658 filed on Jan. 30, 2004; the entire contents of which are incorporated herein by reference.
- 1. Field of the Invention
- The present invention relates to a video projector that projects and displays a picture on a screen based on an input video signal, and more specifically, it relates to a video projector capable of adjusting the size and position of a projected picture, and a method for shifting the projected picture.
- 2. Description of the Related Art
- Conventionally, in order to display a picture created with a computer on a display device included in a video projector such as a liquid crystal projector, it is necessary to generate a video signal corresponding to the resolution of the display device, and supply it to the display device.
- Japanese Unexamined Patent Application Publication No. 2003-84738, for example, discloses an apparatus that can perform display regardless of the resolution of the input video signal. The apparatus measures the frequency of the synchronizing signals in the input video signal; determines the resolution of the video signal based on the measured frequency; and performs video scaling, that is to say, changes (scales) the determined resolution of the video signal so as to agree to the resolution of the display device, thus enabling to display it on the display device.
- Such a video projector includes a video-signal processing unit for changing the input analog video signal to a digital video signal; a scaler unit for scaling the number of pixels of the digital video signal to the number of pixels of the display device; a display-device drive unit for making the display device display a picture based on the digital video signal; a display device, such as a liquid crystal panel, functioning as a light valve; a lamp for emitting light to the display device; and a projection lens for projecting the picture displayed on the display device onto a screen.
- In the case where the display device is a transmissive panel such as a liquid crystal panel, the light emitted from the lamp is transmitted by the display device, is refracted by the projection lens, and forms a projection image on the screen. In the case where the display device is a reflective panel such as a DMD (trademark), the light emitted from the lamp is reflected by the display device, is refracted by the projection lens, and forms a projection image on the screen. DMD (trademark) is an abbreviation of digital micromirror device, and is used in DLP light processing technology. DLP (trademark) is an abbreviation of digital light processing.
- If the projection lens is provided with a mechanism for shifting the lens in the direction of the axis of projection, an “optical zooming operation”, which adjusts the size of the picture projected on the screen, can be performed.
- If the projection lens is provided with a mechanism for shifting the lens in the direction perpendicular to the axis of projection, a “lens shifting operation”, which adjusts the position of the picture projected on the screen, can be performed.
- There are two modes of use for a video projector, that is to say, permanent installation in a room with a fixed screen and temporary installation in various places. Especially in the case of the temporary installation, it is preferable to expand the range of choice for installation places, that is to say, it is preferable that the video projector project a picture on a screen (or a wall used as a screen) regardless of the size, position, and distance of the screen.
- As described above, the optical zooming operation adjusts the size of the picture projected on the screen; and the lens shifting operation adjusts the position of the picture projected on the screen. If the video projector has the mechanisms for the optical zooming and shifting operations, the range of choice for installation places is expanded.
- However, since the lens shifting mechanisms are expensive, there is a need for a method for adjusting the size and position of the projected picture in another way.
- It is an object of the present invention to provide a video projector capable of adjusting the size and position of the projected picture according to the user's operation without using lens-shifting mechanisms, thereby expanding the range of choice for installation places; and a method for shifting the projected picture.
- In one aspect of the present invention, a video projector includes a scaler unit, a display device, a projection lens, and a control unit. The scaler unit writes an input video signal into a frame memory. The scaler unit is capable of scaling the number of pixels of the input video signal to any number of pixels when the input video signal is read out from the frame memory, and outputs the video signal. The display device displays a picture based on the video signal whose number of pixels is scaled by the scaler unit. The projection lens projects the picture displayed on the display device onto a screen. The control unit controls the scaler unit. The scaler unit scales the number of pixels of the input video signal to a smaller number of pixels than the maximum displayable number of pixels of the display device. The scaler unit shifts the picture displayed on the display device to a desired position in the displayable region on the display device by changing the timing of the vertical and horizontal superimposition of the video signal according to an instruction from an operating device so as to shift the picture projected on the screen.
- In one aspect of the present invention, the scaler unit scales the number of pixels of the input video signal to a smaller number of pixels than the maximum displayable number of pixels of the display device, and shifts the picture displayed on the display device to a desired position in the displayable region on the display device, thereby shifting the picture projected on the screen. The size and position of the picture projected on the screen can be adjusted without using lens-shifting mechanisms. Therefore, the range of choice for installation places is expanded.
- Since no lens shifting mechanisms are used, the cost is reduced. When the number of pixels of the video signal is scaled to a smaller number than that of the display device with the scaler unit, the picture displayed on the display device can be shifted. Since the size and position of the picture projected on the screen can be adjusted, the range of choice for installation places is expanded.
- According to the other aspect of this invention, the video projector may further include a shifting mechanism capable of shifting the projection lens at least in the direction of the axis of projection or in the direction perpendicular to the axis of projection.
- In this aspect, in addition to the digital zooming operation and the digital shifting operation performed by the scaler unit and the control unit, the optical zooming operation and the lens shifting operation are performed by combining the shifting mechanism. Therefore, the size and position of the picture projected on the screen can be adjusted over a wider range.
- In the former aspect of the present invention, there is provided a method for shifting a picture projected on a screen by a video projector. The video projector includes a scaler unit and a display device. The scaler unit is capable of scaling the number of pixels of an input video signal to any number of pixels. The display device functions as a light valve and displays a picture based on the video signal whose number of pixels is scaled by the scaler unit. The method comprises the adjustment of the number of pixels of the input video signal to a smaller number of pixels than the maximum displayable number of pixels of the display device so as to adjust the size of the picture projected on the screen; and the adjustment of the position of the picture projected on the screen by the adjusted picture displayed on the display device to a desired position in the displayable region on the display device.
- Since no lens shifting mechanisms are used, the cost is reduced. When the number of pixels of the video signal is made smaller than that of the display device with the scaler unit, the picture displayed on the display device can be shifted. Since the size and position of the picture projected on the screen can be adjusted, the range of choice for installation places is expanded.
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FIGS. 1A to 1C are block diagrams showing an outline of the structure of a video projector of a first embodiment of the present invention.FIG. 1A shows the case where the number of pixels of the video signal is scaled by a scaler unit to the number of pixels of a display device.FIG. 1B shows the case where the number of pixels of the video signal is scaled by the scaler unit to a smaller number of pixels than the number of pixels of the display device. FIG. 1C shows the case where the number of pixels of the video signal is scaled by the scaler unit to a smaller number of pixels than the number of pixels of the display device, and the picture is shifted. -
FIG. 2 is a block diagram showing, in more detail, the structure of the main part of the video projector inFIGS. 1A to 1C. -
FIG. 3 shows the number of pixels (picture size) of the SVGA signal, which is an example of the video signals input into an input-video-signal processing unit. -
FIGS. 4A to 4C illustrate the pictures that can be displayed on the XGA-sized display device when the SVGA-sized video signal shown inFIG. 3 is input.FIG. 4A shows the case where the full screen mode (N=1.28) is selected.FIG. 4B shows the case where the size scaling mode (N=1) is selected.FIG. 4C shows the case where the size scaling mode (N=1) is selected, and the picture is shifted. -
FIGS. 5A to 5F are timing charts in an output timing generator illustrating the display operation inFIG. 4B .FIG. 5A shows the horizontal synchronizing signal;FIG. 5B shows the vertical synchronizing signal;FIG. 5C shows the video signal;FIG. 5D shows the clock signal;FIG. 5E shows the horizontal synchronizing signal; andFIG. 5F shows the video signals for R, G, and B. -
FIGS. 6A to 6F are timing charts in the output timing generator illustrating the display operation inFIG. 4C .FIG. 6A shows the horizontal synchronizing signal;FIG. 6B shows the vertical synchronizing signal;FIG. 6C shows the video signal;FIG. 6D shows the clock signal;FIG. 6E shows the horizontal synchronizing signal; andFIG. 6F shows the video signals for R, G, and B. -
FIGS. 7A to 7C are block diagrams showing an outline of the structure of a video projector of a second embodiment of the present invention.FIG. 7A shows the case where a projection lens is shifted by a shifting mechanism to a predetermined position.FIG. 7B shows the case where the projection lens is shifted by the shifting mechanism back and forth.FIG. 7C shows the case where the projection lens is shifted by the shifting mechanism in the vertical direction. - The preferred embodiments of the present invention will now be described with reference to the drawings.
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FIGS. 1A to 1C are block diagrams showing an outline of the structure of a video projector of a first embodiment of the present invention. - In
FIGS. 1A to 1C, an analog video signal is input into aninput terminal 11 to be supplied to an input-video-signal processing unit 12. The input-video-signal processing unit 12 has an A/D converter, which converts the input analog signal into a digital signal. The digital video signal from the input-video-signal processing unit 12 is supplied to ascaler unit 13. Thescaler unit 13 scales the number of pixels of the digital video signal from the input-video-signal processing unit 12 to the number of pixels of adisplay device 15 or a smaller number of pixels. - Incidentally, the
scaler unit 13 can scale the number of pixels of the digital video signal from the input-video-signal processing unit 12 to a larger number of pixels than the number of pixels of thedisplay device 15. That is to say, thescaler unit 13 can increase the number of pixels by interpolation based on the pixels around a pixel. However, in this case, the entire picture cannot be displayed on the display device. Therefore, normally, thescaler unit 13 does not scale the number of pixels of the digital video signal from the input-video-signal processing unit 12 to a larger number of pixels than the number of pixels of thedisplay device 15. - The digital video signal whose number of pixels is scaled by the
scaler unit 13 is input into a display-device drive unit 14. The display-device drive unit 14 is composed of horizontal and vertical drivers. The display-device drive unit 14 supplies thedisplay device 15 with the digital video signal scaled by thescaler unit 13 to the number of pixels of the display device or a smaller number of the pixels to make thedisplay device 15 display the picture. Thedisplay device 15 is a liquid crystal panel or a DMD (trademark). By emitting light to thisdisplay device 15 from alamp 16, thedevice 15 functions as a light valve. By emitting light to thisdisplay device 15 from thelamp 16, the picture displayed on thedisplay device 15 is light-modulated. The picture is then expanded by aprojection lens 17 and projected on ascreen 18. - In the case where the
display device 15 is a transmissive panel such as a liquid crystal panel, the light emitted from thelamp 16 is transmitted by thedisplay device 15, is refracted by theprojection lens 17, and forms a projection image on thescreen 18. In the case where thedisplay device 15 is a reflective panel such as a DMD (trademark), the light emitted from thelamp 16 is reflected by thedisplay device 15, is refracted by theprojection lens 17, and forms a projection image on thescreen 18. - Incidentally, the DMD (trademark) is an optical semiconductor chip that is at the heart of the digital light processing (DLP (trademark)) technology provided by Texas Instruments Incorporated. The chip has about 500,000 to 1,310,000 microscopic mirrors modulating light and mounted on a standard logic device. The mirrors reflect the light from the lamp to project it on the screen. A DMD is an abbreviation of digital micromirror device.
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FIG. 1A shows the case where the number of pixels of the digital video signal is scaled by thescaler unit 13 to the number of pixels of thedisplay device 15.FIG. 1B shows the case where the number of pixels of the digital video signal is scaled by thescaler unit 13 to a smaller number of pixels than the number of pixels of thedisplay device 15. It is possible that the number of pixels of the input digital video signal is smaller than the number of pixels of thedisplay device 15, and the number of pixels of the input digital video signal is increased by thescaler unit 13. Even in this case, however, the number of pixels of the input digital video signal needs to be scaled by thescaler unit 13 to a smaller number of pixels than the number of pixels of thedisplay device 15.FIG. 1C shows the case where the number of pixels of the digital video signal is scaled by thescaler unit 13 to a smaller number of pixels than the number of pixels of thedisplay device 15, and the picture is shifted. - As shown in
FIG. 1A , when the number of pixels of the digital video signal is scaled by thescaler unit 13 to the number of pixels of thedisplay device 15, the projected picture can fill thescreen 18. - As shown in
FIG. 1B , when the number of pixels of the digital video signal is scaled by thescaler unit 13 to a smaller number of pixels than the number of pixels of thedisplay device 15, a “digital zooming operation” can be performed, that is to say, the size of the picture projected on thescreen 18 can be adjusted. In the digital zooming operation, the number of pixels of the digital video signal is scaled to a smaller number of pixels than the number of pixels of thedisplay device 15, and the reduced picture is displayed in a predetermined position (the central position or another fixed position) on thedisplay device 15. -
FIG. 1C illustrates the most characteristic operation in the first embodiment. As shown inFIG. 1C , the number of pixels of the digital video signal is scaled by thescaler unit 13 to a smaller number of pixels than the number of pixels of thedisplay device 15, and the reduced picture is displayed in the central position (or another fixed position) on thedisplay device 15; thereafter, the user can move the reduced picture to a desired position on thedisplay device 15 by operating an operatingdevice 20, such as an infrared remote control, to control thescaler unit 13. In this way, a “digital shifting operation”, that is to say, vertical and horizontal shifting of the picture projected on thescreen 18 is achieved. -
FIG. 2 is a block diagram showing, in more detail, the structure of the main part of the video projector inFIGS. 1A to 1C. - In
FIG. 2 , the input-video-signal processing unit 12 has twoinput terminals input terminals DVD player 22, respectively. ThePC 21 outputs an analog RGB signal. The analog RGB signal is converted by an A/D converter 121 into a digital RGB signal. The digital RGB signal is input into an input terminal a of aswitching circuit 123. TheDVD player 22 outputs an analog television signal (hereinafter referred to as analog TV signal). The analog TV signal is converted by avideo decoder 122 into a digital RGB signal. The digital RGB signal is input into the other input terminal b of theswitching circuit 123. - The
control unit 19 is a microcomputer, and it performs control operation according to the program stored in the ROM therein. Thecontrol unit 19 counts the number of picture data items (pixel data) in the horizontal period with a determining device provided in the A/D converter 121, thereby determining the number of pixels (product of the horizontal number of pixels and the vertical number of pixels) of the video signal input from thePC 21, that is to say, the resolution of the input video signal. In addition, thecontrol unit 19 measures the number of vertical lines and the frequencies of the horizontal and vertical synchronizing signals with another determining device provided in thevideo decoder 122, thereby determining the number of pixels (product of the horizontal number of pixels and the vertical number of pixels) of the video signal input from theDVD player 22, that is to say, the resolution of the input video signal. Moreover, thecontrol unit 19 makes theswitching circuit 123 perform switching according to the user's operation of the operatingdevice 20. - The digital RGB signal from the switching
circuit 123 is input into thescaler unit 13. - Hereinafter, in order to simplify the description, it is assumed that the digital RGB signal from the
PC 21 is chosen in theswitching circuit 123. - In addition, it is assumed that the
PC 21 outputs the SVGA signal having a number of pixels equal to 800×600 dots, as shown inFIG. 3 , and the maximum number of pixels that thedisplay device 15 can display is the XGA-size of 1024×768 dots. In this case, in order to fill thedisplay device 15 with the video signal from thePC 21, it is necessary to multiply the number of pixels by 1.28 in both the horizontal and vertical directions. - The
scaler unit 13 has ascaler 131 and aframe memory 132. Thescaler 131 has a first function and a second function. The first function is to adjust the size of the picture projected on the screen (not shown) by scaling the number of pixels of the input digital RGB signal. The second function is carried out when the number of pixels of the input digital RGB signal is scaled by the first function to a smaller number of pixels than the number of pixels of thedisplay device 15. The second function is to shift the picture projected on the screen (not shown) by moving the picture displayed on thedisplay device 15 to a desired position according to the user's instruction via the operatingdevice 20. Theframe memory 132 has a capacity capable of storing at least one frame of the input digital RGB signal. - The
scaler 131 and theframe memory 132 constitute a frame-rate converter capable of converting the frequency of the output digital RGB signal to a frequency suitable for thedisplay device 15 regardless of the frequency of the input digital RGB signal. - The
scaler 131 has an N-multiplyingcircuit 131A and anoutput timing generator 131B. The N-multiplyingcircuit 131A scales (increases or decreases) the number of pixels of the digital RGB signal by interpolation or pixel skipping when the input digital RGB signal is read out from theframe memory 132, thereby multiplying the number of pixels of the digital RGB signal displayed on thedisplay device 15 by N. In the case of expansion, N>1, and in the case of reduction, 0<N<1. Theoutput timing generator 131B moves the picture displayed on thedisplay device 15 to a desired position in the displayable region on thedisplay device 15 under the control of thecontrol unit 19 based on the user's instruction via the operatingdevice 20 when the number of pixels of the input digital RGB signal is scaled by the N-multiplyingcircuit 131A to a smaller number of pixels than the maximum displayable number of pixels of thedisplay device 15, thereby shifting the picture projected on the screen (not shown). In the case where the resolution of thedisplay device 15 is XGA (1024×768 dots), theoutput timing generator 131B is caused by thecontrol unit 19 to constantly output the XGA-sized signal even if the number of pixels of the picture is multiplied by N by the N-multiplyingcircuit 131A. Incidentally, “to multiply by N” in the above description includes the case where N=1, that is to say, the number of pixels is unchanged. The operation of thescaler 131 will hereinafter be described with reference toFIG. 5 . - The XGA-sized digital RGB signal output from the
scaler unit 13 is input into the display-device drive unit 14. - Under the control of the
control unit 19, and by using the input digital RGB signal, the display-device drive unit 14 drives thedisplay device 15, which is constituted of an XGA-sized liquid crystal panel, to perform display. Since thecontrol unit 19 already knows the resolution of thedisplay device 15, thecontrol unit 19 only performs the display-device drive unit 14 predetermined display control suitable for the resolution of thedisplay device 15. -
FIGS. 4A to 4C illustrate the pictures that can be displayed on the XGA-sized display device 15 inFIG. 2 when the SVGA-sized (800×600 dots) video signal shown inFIG. 3 is input from thePC 21. The case where the number of pixels is unchanged (that is to say, N=1) will be included in the description with reference toFIGS. 4A to 4C. -
FIG. 4A shows the case where the full screen mode (N=1.28) is chosen by the operatingdevice 20. In this case, N is set to 1.28 in the N-multiplyingcircuit 131A; the N-multiplyingcircuit 131A changes the SVGA-sized video signal from thePC 21 to the XGA-sized video signal by multiplying the number of pixels by 1.28 both in the horizontal direction and the vertical direction; and theoutput timing generator 131B automatically makes the XGA-sized video signal fill the XGA-sized display device 15. -
FIG. 4B shows the case where the size scaling mode (N=1) is selected by the operatingdevice 20. In this case, N is set to 1 in the N-multiplyingcircuit 131A; the N-multiplyingcircuit 131A does not change the SVGA-sized video signal from thePC 21; and theoutput timing generator 131B superimposes the unchanged SVGA-sized video signal on the XGA-sized black signal so as to place the video signal part at the center of the XGA-sized display device 15. The XGA-sized black signal and the horizontal and vertical synchronizing signals are generated in theoutput timing generator 131B. The shaded part is the black signal part. - Although
FIG. 4B shows the case where N=1, more generally, in the case where the number of pixels of the input video signal is scaled to a smaller number of pixels than the number of pixels of thedisplay device 15, thecontrol unit 19 controls theoutput timing generator 131B so that the picture part is disposed in the center of thedisplay device 15. -
FIG. 4C shows the case where the size scaling mode (N=1) is selected by the operatingdevice 20, and the picture is shifted using the arrow keys (upward, downward, rightward, and leftward) of the operatingdevice 20. In this case, N is set to 1 in the N-multiplyingcircuit 131A; the N-multiplyingcircuit 131A does not change the SVGA-sized video signal from thePC 21; theoutput timing generator 131B superimposes the unchanged SVGA-sized video signal on the XGA-sized black signal so as to place the video signal part at the center of the XGA-sized display device 15; and then the picture part is shifted with the arrow keys so as to be located in the upper center of thedisplay device 15. The shaded part is the black signal part. With the arrow keys of the operatingdevice 20, the picture based on the SVGA-sized video signal can be moved to any position on thedisplay device 15, for example, to the lower right position shown with the dotted line inFIG. 4C . - Next, the displaying operation in
FIGS. 4B and 4C will be described with reference to the timing charts of theoutput timing generator 131B shown inFIGS. 5A to 5F and 6A to 6F. The number of pixels of the input digital video signal supplied to theoutput timing generator 131B is herein assumed to be a smaller number of pixels than the displayable number of pixels of thedisplay device 15. -
FIGS. 5A to 5F are timing charts in theoutput timing generator 131B illustrating the displaying operation inFIG. 4B . -
FIGS. 5A to 5C illustrate the vertical timing in which the video signal is superimposed on the black signal (denoted by ‘0’) generated in theoutput timing generator 131B.FIG. 5A shows the horizontal synchronizing signal generated in theoutput timing generator 131B.FIG. 5B shows the vertical synchronizing signal generated in theoutput timing generator 131B.FIG. 5C shows the video signal superimposed on the black signal (denoted by ‘0’) generated in theoutput timing generator 131B. The arrow indicates the vertical picture-starting-position. -
FIGS. 5D to 5F illustrate the horizontal timing at which the video signals R, G, and B are superimposed on the black signal (denoted by ‘0’) generated in theoutput timing generator 131B.FIG. 5D shows the clock signal generated in theoutput timing generator 131B, the signal having a period corresponding to one pixel of thedisplay device 15.FIG. 5E shows the horizontal synchronizing signal generated in theoutput timing generator 131B.FIG. 5E shows one of the horizontal synchronizing periods inFIG. 5A enlarged. The horizontal synchronizing period shown inFIG. 5E shows the period of the horizontal synchronizing signal enlarged including the horizontal picture-starting-position. In the period of the vertical synchronizing period shown inFIG. 5B which corresponds to one screen period.FIG. 5F shows the video signals R, G, and B superimposed on the black signal (denoted by ‘0’) generated in theoutput timing generator 131B. - In
FIGS. 5C and 5F , the arrows indicate the vertical picture-starting-position and the horizontal picture-starting-position, respectively. InFIG. 5F , ‘0’ denotes the level of the video signals R, G, and B in each pixel in the black part; and ‘50’, ‘25’, and ‘70’ denote the level of the video signals R, G, and B, respectively, in the pixel where the video signals start to be superimposed. - As shown in
FIGS. 5A to 5C, the horizontal synchronizing periods in the first stage of one vertical synchronizing period are filled with black signals; the video signal is superimposed in the middle stage of each of the horizontal synchronizing periods in the middle stage of one vertical synchronizing period; and the horizontal synchronizing periods in the latter stage of one vertical synchronizing period are filled with black signals. Consequently, the input video signal inFIG. 3 is displayed in the center of thedisplay device 15, as shown inFIG. 4B . Since the level of these signals is represented with 8 bits, the level is in the range of 0 to 255. -
FIGS. 6A to 6F are timing charts in theoutput timing generator 131B illustrating the displaying operation inFIG. 4C . -
FIGS. 6A to 6C illustrate the vertical timing in which the video signal is superimposed on the black signal (denoted by ‘0’) generated in theoutput timing generator 131B.FIG. 6A shows the horizontal synchronizing signal generated in theoutput timing generator 131B.FIG. 6B shows the vertical synchronizing signal generated in theoutput timing generator 131B.FIG. 6C shows the video signal superimposed on the black signal (denoted by ‘0’) generated in theoutput timing generator 131B. The arrow indicates the vertical picture-starting-position. -
FIGS. 6D to 6F illustrate the horizontal timing at which the video signals R, G, and B are superimposed on the black signal (denoted by ‘0’) generated in theoutput timing generator 131B.FIG. 6D shows the clock signal generated in theoutput timing generator 131B, the signal having a period corresponding to one pixel of thedisplay device 15.FIG. 6E shows the horizontal synchronizing signal generated in theoutput timing generator 131B.FIG. 6E shows one of the horizontal synchronizing periods inFIG. 6A enlarged. The horizontal synchronizing period shown inFIG. 6E shows the period of the horizontal synchronizing signal enlarged including the horizontal picture-starting-position. In the period of the vertical synchronizing period shown inFIG. 6B which corresponds to one screen period.FIG. 6F shows the video signals R, G, and B superimposed on the black signal (denoted by ‘0’) generated in theoutput timing generator 131B. - In
FIGS. 6C and 6F , the arrows indicate the vertical picture-starting-position and the horizontal picture-starting-position, respectively. InFIG. 6F , ‘0’ denotes the level of the video signals R, G, and B in each pixel in the black part; and ‘50’, ‘25’, and ‘70’ denote the level of the video signals R, G, and B, respectively, in the pixel where the video signals start to be superimposed. - As shown in
FIGS. 6A to 6C, the video signal is superimposed in the middle stage of each of the horizontal synchronizing periods in the first stage of one vertical synchronizing period; and the horizontal synchronizing periods in the latter stage of one vertical synchronizing period are filled with black signals. Consequently, the input video signal inFIG. 3 is displayed in the upper center of thedisplay device 15, as shown inFIG. 4C . - In the above embodiment, the video signal input from the
PC 21 into the input-video-signal processing unit 12 is the SVGA signal having a number of pixels equal to 800×600 dots. In the case where the signal having a number of pixels equal to, for example, 1600×1200 dots is input, in order to fill the XGA-sized (1024×768)display device 15, it is necessary to perform pixel skipping (N=0.64) in the N-multiplyingcircuit 131A. In order to display the signal in part of the XGA-sized (1024×768)display device 15, of course, it is necessary to perform further pixel skipping by setting (N<0.64) in the N-multiplyingcircuit 131A. All of these resizing processes can be performed in thescaler unit 13. - Since the first embodiment has no lens-shifting mechanisms, the cost is reduced. When the number of pixels of the video signal is made smaller than that of the display device with the scaler, the picture displayed on the display device can be shifted vertically and horizontally with the scaler according to the user's operation. Therefore, the range of choice for installation places is expanded.
-
FIGS. 7A to 7C are block diagrams showing an outline of the structure of a video projector of a second embodiment of the present invention. - The second embodiment shown in
FIGS. 7A to 7C has ashifting mechanism 21 provided for theprojection lens 17 in the first embodiment. Therefore, the second embodiment is capable of optical zooming operation and lens shifting operation. The remaining structure is the same as the first embodiment shown inFIGS. 1A to 1C. The shiftingmechanism 21 at least has a mechanism for shifting in the direction of the axis of projection back and forth and a mechanism for shifting in the direction perpendicular to the axis of projection up and down. Therefore, in addition to the digital zooming operation and the digital shifting operation in the first embodiment, the second embodiment is capable of optical zooming operation and lens shifting operation by the shiftingmechanism 21. -
FIG. 7A is the same asFIG. 1A , except for theshifting mechanism 21 for the lens. Theprojection lens 17 inFIG. 1A is provided with ashifting mechanism 21 that can move thelens 17 at least in the vertical and horizontal directions. The user manually operates an adjusting device (not shown), such as a dial, for controlling theshifting mechanism 21, thereby performing the optical zooming operation, which can adjust the size of the projected picture, and the lens shifting operation, which can adjust the position of the projected picture. -
FIG. 7A shows theprojection lens 17 disposed in a predetermined position by the shiftingmechanism 21. -
FIG. 7B shows that the optical zooming operation, which adjusts the size of the picture projected on thescreen 18, is performed by moving theprojection lens 17 from the position shown with a dotted line (the lens position inFIG. 1A , for example) in the direction of the axis of projection by the shiftingmechanism 21. -
FIG. 7C shows that the lens shifting operation, which adjusts the position of the picture projected on thescreen 18, is performed by moving theprojection lens 17 from the position shown with a dotted line (the lens position inFIG. 1A ) in the direction perpendicular to the axis of projection with the shiftingmechanism 21. - In addition, as in the first embodiment in
FIGS. 1A to 1C, the digital zooming operation and the digital shifting operation can also be performed. As described above, the digital zooming operation scales the number of pixels of the video signal with thescaler unit 13 to a number of pixels equal to or smaller than the number of pixels of thedisplay device 15, thereby adjusting the size of the picture projected on thescreen 18. In the case where the number of pixels of the video signal is scaled to a smaller number of pixels than the number of pixels of thedisplay device 15, the digital shifting operation moves the video signal to a desired position in the displayable region on thedisplay device 15, thereby adjusting the position of the picture projected on thescreen 18. Therefore, the size and position of the picture projected on thescreen 18 can be adjusted both digitally and optically. - In addition to the digital zooming operation and the digital shifting operation in the first embodiment, the second embodiment can perform the optical zooming operation and the lens shifting operation by the shifting
mechanism 21 for theprojection lens 17. Therefore, the second embodiment can adjust the size and position of the projected picture over a wider range. Consequently, the range of choice for installation places is expanded. - The present invention is useful for an image projector such as a liquid crystal projector and a DMD (trademark) to adjust the size and position of the picture projected on the screen.
- Having described the preferred embodiments of the invention referring to the accompanying drawings, it should be understood that the present invention is not limited to those precise embodiments and various changes and modifications thereof could be made by one skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims.
Claims (5)
1. A video projector comprising:
a scaler unit for writing an input video signal into a frame memory, the scaler unit being capable of scaling the number of pixels of the input video signal to any number of pixels when the input video signal is read out from the frame memory;
a display device for displaying a picture based on the video signal whose number of pixels is scaled by the scaler unit;
a projection lens for projecting the picture displayed on the display device onto a screen; and
a control unit for controlling the scaler unit, the scaler unit scaling the number of pixels of the input video signal to a smaller number of pixels than the maximum displayable number of pixels of the display device, the scaler unit shifting the picture displayed on the display device to a desired position in the displayable region on the display device by changing the timing of the vertical and horizontal superimposition of the video signal according to an instruction from an operating device so as to shift the picture projected on the screen.
2. The video projector according to claim 1 , wherein the scaler unit comprising:
an N-multiplying device for scaling the number of pixels of the input video signal by multiplication to a smaller number of pixels than the maximum displayable number of pixels of the display device when the input video signal is read out from the frame memory; and
an output-timing generating device for changing the timing of the vertical and horizontal superimposition of the video signal according to the position instruction from the operating device so as to shift the picture displayed on the display device to a desired position in the displayable region on the display device.
3. The video projector according to claim 1 , further comprising a shifting mechanism capable of shifting the projection lens at least back and forth in the direction of the axis of projection up and down or in the direction perpendicular to the axis of projection.
4. The video projector according to claim 2 , further comprising a shifting mechanism capable of shifting the projection lens at least back and forth in the direction of the axis of projection or up and down in the direction perpendicular to the axis of projection.
5. A method for shifting a picture projected on a screen by a video projector, the video projector including a scaler unit and a display device, the scaler unit being capable of scaling the number of pixels of an input video signal to any number of pixels, the display device functioning as a light valve and displaying a picture based on the video signal whose number of pixels is scaled by the scaler unit, the method comprising:
the adjustment of the number of pixels of the input video signal to a smaller number of pixels than the maximum displayable number of pixels of the display device so as to adjust the size of the picture projected on the screen; and
the adjustment of the position of the picture projected on the screen by moving the adjusted picture displayed on the display device to a desired position in the displayable region on the display device.
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JP2004024658A JP2005215542A (en) | 2004-01-30 | 2004-01-30 | Video projector device and method for adjusting position of projection video thereof |
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US20050168698A1 true US20050168698A1 (en) | 2005-08-04 |
US7237903B2 US7237903B2 (en) | 2007-07-03 |
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